Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A projection apparatus comprising: an optical circuit including a light source unit; a signal processing circuit configured to generate an input video signal; and a laser driving circuit including: a laser driving video current generating circuit for generating a laser driving current for driving the light source unit; a high-frequency superimposing section configured to superimpose a high-frequency signal of a frequency exceeding a band of the input video signal on the laser driving current generated by the laser driving video current generating circuit; and a receiver in the high-frequency superimposing section, the receiver is configured to receive a clock signal input from an outside of the laser driving circuit in a state of being synchronized with the input video signal as a signal source of the high-frequency signal, wherein a frequency of the high-frequency signal is synchronized with a pixel period.
A projection apparatus reduces laser speckle by modulating the laser driving current with a high-frequency signal. The apparatus contains a light source unit, a signal processing circuit that generates an input video signal, and a laser driving circuit. The laser driving circuit includes a video current generator and a high-frequency superimposing section. The superimposing section adds a high-frequency signal (frequency exceeding the video signal's bandwidth) to the laser driving current. The high-frequency signal is synchronized with the input video signal's pixel period, using a clock signal received from outside the laser driving circuit as its source. This clock signal is synchronized with the input video signal.
2. A projection apparatus according to claim 1 , wherein the clock signal is synchronized with the input video signal before the high-frequency superimposing section receives the clock signal.
The projection apparatus, as described with speckle reduction achieved by superimposing a high-frequency signal onto the laser driving current, where the high-frequency signal is synchronized with the input video signal, specifies that the clock signal used for generating the high-frequency signal is synchronized with the input video signal *before* it is received by the high-frequency superimposing section. This ensures accurate synchronization.
3. A projection apparatus according to claim 1 , wherein the light source unit is controllable by the laser driving current to emit different wavelengths of light.
The projection apparatus, as described with speckle reduction achieved by superimposing a high-frequency signal onto the laser driving current, where the high-frequency signal is synchronized with the input video signal, uses a light source unit that can emit laser light of different wavelengths, and this emission is controllable by the laser driving current. Therefore the laser driving current is not only modulated for speckle reduction, but also controls the color output of the projector.
4. A projection apparatus according to claim 1 , wherein the high-frequency superimposing section is configured to superimpose the high-frequency signal on the laser driving current by switching the input video signal input to the laser driving video current generating circuits according to the high-frequency signal.
The projection apparatus, as described with speckle reduction achieved by superimposing a high-frequency signal onto the laser driving current, where the high-frequency signal is synchronized with the input video signal, implements the high-frequency superimposition by rapidly switching the input video signal provided to the laser driving video current generating circuits, using the high-frequency signal as the switching control. This method directly modulates the video input based on the high-frequency signal.
5. A projection apparatus according to claim 1 , wherein the high-frequency superimposing section is configured to perform a process of superimposing the high-frequency signal on the laser driving current on an input side of the laser driving video current generating circuits.
The projection apparatus, as described with speckle reduction achieved by superimposing a high-frequency signal onto the laser driving current, where the high-frequency signal is synchronized with the input video signal, performs the high-frequency superimposition *before* the input video signal reaches the laser driving video current generating circuits. This means the high-frequency modulation is applied to the input signal itself.
6. A projection apparatus according to claim 1 , wherein the high-frequency superimposing section is configured to perform a process of superimposing the high-frequency signal on the laser driving current on an output side of the laser driving video current generating circuits.
The projection apparatus, as described with speckle reduction achieved by superimposing a high-frequency signal onto the laser driving current, where the high-frequency signal is synchronized with the input video signal, performs the high-frequency superimposition *after* the laser driving video current generating circuits have generated the laser driving current. Thus, the high-frequency signal is added to the current signal rather than modulating the input video signal.
7. A projection apparatus according to claim 1 , wherein the high-frequency superimposing section is configured to superimpose the high-frequency signal on the laser driving current by adding output current of the laser driving superimposing current generating circuit to the laser driving current generated by the laser driving video current generating circuits.
The projection apparatus, as described with speckle reduction achieved by superimposing a high-frequency signal onto the laser driving current, where the high-frequency signal is synchronized with the input video signal, uses a separate laser driving superimposing current generating circuit to generate the high-frequency signal. The output current of *this* circuit is then added to the laser driving current produced by the main laser driving video current generating circuits.
8. A projection apparatus according to claim 1 , wherein a level change detecting circuit is configured to detect the level change of the input video signal.
The projection apparatus, as described with speckle reduction achieved by superimposing a high-frequency signal onto the laser driving current, where the high-frequency signal is synchronized with the input video signal, includes a level change detecting circuit. This circuit monitors the input video signal and detects changes in its signal level. This detected level change may then control the high frequency superimposition, potentially to more closely match the high frequency dithering with the video content itself.
9. A projection apparatus according to claim 1 , wherein an oscillator is configured to oscillate the high-frequency signal on a basis of a signal synchronized with the input video signal.
The projection apparatus, as described with speckle reduction achieved by superimposing a high-frequency signal onto the laser driving current, where the high-frequency signal is synchronized with the input video signal, contains an oscillator. This oscillator generates the high-frequency signal, basing its oscillations on a signal that is synchronized with the input video signal. This synchronization ensures the high-frequency modulation remains tied to the video content.
Unknown
November 7, 2017
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